Method and apparatus for flowing crude oil from a well

ABSTRACT

Method and apparatus for flowing crude oil from wells wherein a fluid is injected into the oil bearing earth formation for the purpose of reducing the viscosity of the oil and causing it to migrate under induced formation pressure to one or more production wells. The apparatus and method are employed in the production wells in such manner that flashing of high temperature water to steam is selectively induced in the apparatus and in the well casing in which the apparatus is located for lightening the fluid column in the apparatus and causing a flowing action to occur and for selectively condensing the steam to its liquid state for liquid transportation of oil within the apparatus. The apparatus is received in the well casing in such a manner that the apparatus and the inner conduit to which it is connected may be removed from the well casing substantially free of any of the hot liquid that is present in the apparatus in the operative condition thereof.

1 1 Mar. 25, 1975 1J nited States Patent Elfarr ABSTRACT [76] Johnnie A.Elfarr, PO. Box 901,

Palestine, Tex. 75801 Sept. 19, 1973 Method and apparatus for flowingcrude oil from wells wherein a fluid is injected into the oil bearingearth [22] Filed: formation for the purpose of reducing the viscosity of1 App! NO: 398,571 the oil and causing it to migrate under inducedformation pressure to one or more production wells. The apparatus andmethod are employed in the production wells in such manner that flashingof high temperature water to steam is selectively induced in theapparatus E2lb and in the well casing in which the apparatus is locatedfor lightening the fluid column in the apparatus [51] llnt. Cl.

[58] Field of Search.......... 166/68, 105, 244 R, 314;

, 118 and causing a flowing action to occur and for selec- 417/54, 55tively condensing the steam to its liquid state for liquid [56]References Cited transportation of oil within the apparatus. The appara-UNITED STATES PATENTS tus is received in the well casing in such amanner that the apparatus and the inner conduit to which it is con-164267 nected may be removed from the well casing substan- 417/I4Stially free of any of the hot liquid that is present in the apparatus inthe operative condition thereof.

18 Claims, 5 Drawing Figures Primary ExaminerFrank L. Abbott AssistantE.\'cm1inerJack E. Ebel CONTROL LE R PATENTED 3873,238 snmapfi z FIGS746 CON TROL L E R METHOD AND APPARATUS FOR FLOWING CRUDE OIL FROM AWELL FIELD OF THE INVENTION This invention is directed generally toapparatus for production or secondary recovery of crude oil from earthformations having insufficient formation pressure for raising the crudeoil to the surface of the earth and wherein the crude oil within theearth formation is of sufficient viscosity to prevent it from readilymigrating to production wells. More particularly the invention isdirected to a pneumatic displacement method of primary or secondaryrecovery of crude oil wherein air or steam is injected into theformation to reduce the viscosity of the crude oil and to develop aformation pressure that causes migration of the oil to production wells.Where steam is injected into the oil bearing formation, the steam may beselectively condensed and vaporized simply by varying the pressurethereof. Specifically, the invention is directed to the provision of amethod and apparatus for pneumatic displacement pumping, incorporating adown-hole valve mechanism and a surface located control facility thatcooperate to inject a pressurized gas into the well to cause selectivevaporization and condensation of hot water within the pumping mechanismto produce controlled displacement pumping of the crude oil entering theproduction well from the formation.

BACKGROUND OF THE INVENTION While the invention will be explained forpurposes of simplicity with regard to its application to production ofoil from oil bearing earth formations having little or no formationpressure, it is considered obvious that the invention may be utilizedeffectively for displacement of other fluids that may or may not belocated within earth formations. The present invention will be discussedin its application solely for the production of oil from oil bearingearth formations for purposes of simplicity and to facilitate readyunderstanding of the invention. It is in no way intended to limit thepresent invention solely to use in connection with production of oil.

When oil bearing earth formations are discovered that have insufficientformation pressure for gas energized production of oil found in theformation, or when a pressurized oil bearing formation loses asubstantial amount of its formation pressure, it will become necessaryto provide for recovery of the oil by methods other than production byformation pressure flowing. One acceptable method for producing lowpressure or zero pressure oil bearing earth formation has been the useof mechanically energized pumps that simply mechanically elevate the oilto the surface of the earth for production by conventional reciprocatingpump mechanisms. These pumps are generally restricted to production ofoil from very shallow oil bearing earth formations and are not capableof pumping a viscous crude oil because viscous crude oil, in absence offormation pressure, will not be capable of migrating through the earthformation to the well bore.

Another method, successfully utilized in production of otherwiseunproducable oil wells, has been the use of pneumatic displacementpumps, which may be also referred to as gas lift valves." These pumps orvalves may be energized by compressed air, compressed inert gases,steam, or compressed natural gas and are effective to achieve productionof oil bearing formations that are of substantial depth. U.S. Pat. Nos.1,326,338 to Gregory, 1,754,945 to Haskell, and 3,106,170 to Gray, eachdisclose pneumatic displacement type devices for flowing or pumping oilwells.

Typically, pneumatic displacement pumps inject a gas into a pumpingmechanism disposed below the fluid level within the well which gasserves a piston like function to raise liquid in the production tubingin the form of a slug or segment. A small amount of the gas, of course,mixes with the liquid to some extent, thereby lightening the load of thecolumn and allowing the column of liquid to be transported to the earthsurface for production.

Where steam is injected into the earth formation, for the purpose ofproviding sufficient heat to reduce the viscosity of the crude oilentrapped in the earth formation and thereby allowing the crude oil tomigrate toward one or more production wells, typically a number ofproduction wells surround a steam injection well. The steam injectedinto the formation will condense to its liquid form, because of thepressure under which it is maintained, whereupon the liquid form willalso migrate through the oil bearing earth formation toward theproduction well. The water at the level of the oil sand in theproduction wells will be in the order of 250 to 350F. Since the watertemperature is above the boiling point of water at atmospheric pressure,reduction of pressure within the well bore at the formation level willcause immediate vaporization of the water to steam. This vaporization istypically referred to in the industry as flashing" and will be soreferred to in the present application.

Where steam is injected into oil bearing earth formation, for thepurpose of reducing the viscosity of the crude oil contained therein andcausing it to migrate to production wells, and air or other gases areinjected into production wells for the purpose of lifting the crude oilor a mixture of crude oil and water to the surface of the earth forproduction, each time the pumping mechanism operates the watercontainedin the production fluid at the bottom of the well, being in the order of250 to 350F will flash to steam, thereby interfering with effectiveproduction of the oil. In fact, the efficiency of producing crude oil inthis manner is typically in the order of 12 percent, thereby renderingpneumatic displacement pumping of hot production fluid having a watercontent to be quite expensive and thereby reducing the commercialfeasibility of recovery of oil in this manner. It is thereforeconsidered desirable to utilize the pressure generated by the watercontent of the hot production fluid to assist in production of the crudeoil. It is also desirable to utilize, as efficiently as possible, theenergy that is required to produce steam and inject it into the oilbearing formation for production purposes.

One problem presented by the use of pneumatic type fluid displacementpumps or flowing devices is the physical dimension of the well casingwithin which the pump mechanisms must be received. Because of thesubstantial physical size of most pneumatic displacement pumps, it isnecessary to provide a well bore and well casing of substantialdimension to allow sufficient space within which the pump may bereceived. Well bores of substantial size are expensive to drill andtherefore detract from the commercial feasibility of pneumaticdisplacement pump type oil recovery systems. It is desirable thereforeto provide a pneumatic.

displacement pump type pumping mechanism that is of relatively smallcross-sectional dimension and which will be efficiently received withina well bore without any requirement for enlargement of the well borebeyond the normal dimension required for receiving conventional wellproduction tubing.

Another problem with some pneumatic displacement pump mechanisms occurswhen the pumping mechanisms are extracted from the well for repair orreplacement. During steam injection for the purpose of enhancingformation pressure and simultaneously increasing the temperature of theformation, thereby reducing the viscosity of the crude oil contained inthe formation and enhancing the ability of the oil to flow from theformation to the production tubing, the formation is heated to atemperature near the temperature of superheated steam and, consequently,and liquid that is trapped within the well tubing as it is extractedfrom the well is quite hot and poses a dangerous condition for workmenaccomplishing the well servicing operation. In most pneumatic wellpumping mechanisms, there is present at the lowermost portion of theWell tubing, one or more check valve mechanisms that seal responsive tothe hydrostatic head of the liquid contained within the tubing, therebycausing the tubing to be pulled from the well full of hot productionfluid trapped therein. The-hazardous condition of such repair operationsis enhanced because the trapped production fluid frequently spills whenthe tubing is separated and presents a safety hazard because of thelikelihood of fire and the generally unsafe conditions that result fromoil spills. Moreover, when the production fluid is extremely hot,because of the steam or fire flooding operations that provide theformation pressure for production and provide heat for reducing theviscosity of the oil to allow it to migrate in the formation, the hotoil/water mixture presents a safety hazard to workmen involved indisassembly of sections of tubing that are filled with the hot fluid.Hot production fluid spilling from fluid filled sections of tubingpresents a safety hazard due to the possibility of causing hot fluidburn injuries to the workmen separating the tubing. It is therefore verydesirable to remove tubing strings from the well that are not filledwith hot liquid.

Accordingly, it is a primary object of the present invention to providea novel method of accomplishing pneumatic displacement of hightemperature fluid from a well which effectively utilizes pressuregenerated by high temperature flashing of water into steam for assistingin elevation of production fluid from a fluid bearing earth formation tothe surface of the earth for production.

It is a further object of the present invention to provide a novelmethod of pneumatic displacement pumping of high temperature watercontaining fluid from a well wherein the water content of the fluid iscaused to selectively flash into steam and condense into its water formfor the purpose of controlled release of pressure that assists inproduction of the fluid from the well.

It is an even further object of the present invention to provide apneumatic displacement type pumping mechanism for flowing oil or anyother production fluid from a well that obviates any necessity forlifting oil filled tubing strings from the well during repair ofreplacement operations.

It is an even further operation of the present invention to providepneumatic displacement type pumping apparatus having down-hole valvesthat may be removed for repair or replacement simply by removing theintermost light-weight tubing string from the well.

Another object of the present invention involves the provision of novelpneumatic displacement type pumping apparatus for flowing hightemperature production fluid from wells which includes valve apparatusand valve seat structures that may be completely removed from the wellin a single operation, simply by removing the centermost light-weighttubing string from the well.

Among the several objects of the present invention is contemplated theprovision of novel pneumatic displacement type pumping apparatus thatmay be effectively utilized in oil wells-of relatively small casingdimension.

It is also an important object of thepresent invention to provide novelpneumatic displacement type pumping apparatus employing a simplecross-over mechanism that promotes efficient pumping operation of theapparatus by cooperating with other structure of the displacementpumping mechanism to cause selective development of pressure changeswithin the pumping mechanism and within the casing to cause'selectiveflashing of the hot water content of the production fluid into steam andcauses selective condensation of steam into water and utilizes theenergy of the steam to assist in transportation of production fluid tothe surface of the earth.

It is an even further object of the present invention to provide novelpneumatic displacement type pumping apparatus for flowing hightemperature water containing oil from a well, which apparatus is simplein nature, reliable in use, and low in cost.

Other and further objects, advantages and features of the presentinvention will become apparent to one skilled in the art uponconsideration of the written specification, the attached claims and theannexed drawings. The form of the invention, which will now be describedin detail, illustrates the general principles of the invention, but itis to be understood that this detailed description is not to be taken aslimiting the scope of the present invention.

SUMMARY OF THE INVENTION A preferred embodiment of the present inventionmay comprise a well casing extending through a drilled bore in the earthto an oil bearing earth formation which well casing may be provided witha well head at its upper extremity and with a perforated element,typically referred to as a screen, at its lower extremity. Oil, or watercontained oil, typically referred to as production fluid, may be forcedby formation pressure, either induced naturally or artificially and mayenter the well casing through the perforations of the screen and mayrise to a level within the casing. Inner and outer conduits may beremovably suspended from a well head at the surface of the earth and mayextend to the production zone within the casing. The outer conduit maybe provided with a landing nipple at its lower extremity and a landingadapter, connected to the inner tubing string, may be received andlocked within the landing nipple in such manner that a sealedrelationship is established between the landing nipple and the landingadapter.

An outer pump conduit may extend downwardly from the landing adapter andmay have a check valve disposed at the lower extremity thereof to allowunidirectional flow of production fluid from the well casing into anouter pump chamber. An inner pump tubing may extend downwardly from thelanding adapter and may be disposed within the outer pump conduit andmay have a check valve disposed at its lower extremity to allowunidirectional flow of production fluid from the outer pump chamber toan inner pump chamber.

The outer pump chamber may be communicated by restricted crossoverpassages to the inner tubing strong supported by the well head and maycooperate with the intertubing string to define a pressure imposingchamber wherein pressurized gas is introduced into the well in order tocause a pneumatic pumping action to occur. The outer chamber below thecrossover mechanism may constitute an outer pumping chamber wherein hotwater disposed therein may be caused to vaporize into steam and providea motive force that causes the flow of oil or oil water mixture disposedwithin the outer pumping chamber to flow through a check valve into theinner pumping chamber. The inner pumping chamber is communicated throughrestricted passages formed in the crossover mechanism to a flow chamberdefined by the annulus between the inner and outer tubing strings withinthe well bore which annulus is, in turn, communicated with a flow lineto conduct produced fluid from the well to a handling or storagefacility. The restricted passageways from the inner pumping chamber tothe flow chamber allow the development of pressure changes to causeflashing of water into steam in the flow chamber which develops apressure condition that assists in transporting fluid within the flowchamber upwardly through the outer tubing string to the flow line.

The inner tubing string is communicated with a pressurized source ofactuating gas such as compressed air, compressed natural gas, or steam,which may be introduced into the well to provide a motive or controlforce for pneumatic displacement pumping ofliquid from the level of theoil bearing earth formation to surface for production through the flowline extending from the well head.

In employing the method of pneumatic type displacement pumping inaccordance with the present invention, a gas may be introduced into theinner conduit or injection'chamber at much lower temperature than thetemperature of the production fluid within the well. The cool gas causescondensation of at least a part of the steam present within the innerconduit at the start of a pumping cycle. The condensed water will flowthrough the crossover mechanism into the outer pumping chamber and steamwithin the outer pumping chamber will'also condense. Pressure within theinner conduit will then be reduced by venting the inner conduit, therebycausing flashing of a portion of the water content within the innerconduit and through the crossover passages will cause vaporization of apart of the water content of the production fluid within the outerpumping chamber, thereby creating sufficient pressure to induce liquidwithin the outer pumping chamber to flow through the check valvemechanism into the inner pumping chamber. The liquid within the innerpumping chamber will then flow through therestricted passages of thecrossover mechanism into a much larger flow chamber defined by theannulus between the inner and outer conduits. This chamber, being ofmuch larger dimension, of course, causes sudden pressure reduction ofthe liquid exiting from the restricted passages of the crossovermechanism and causes a portion of the water content of the liquid soexiting to vaporize or flash immediately to steam. The steam, inaddition to producing a pressure that induces upward flow of productionfluid within the flow chamber to the flow line at the I well head, alsoserves to lighten the column of fluid as to cause an upward flowingaction to occur, thereby transporting oil contained in the mixture tothe well head where it is conducted away through the flow line. Withless than 50 pounds of flow line pressure, the fluid, so produced, willbe transported through the flow line to a storage or handling facility.

The control valves are then manipulated to vent the inner conduit andthe outer pumping chamber in order to reduce pressure therein. As thepressure reduces below the formation pressure, the lower check valve ofthe outer pumping conduit will open because of the pressure differentialthereacross and will communicate the low pressure condition of the outerpumping chamber to the well casing and to the formation. A portion ofthe water content of the hot production fluid within the casing willflash into steam and will force production fluid from the casing intothe outer pumping chamber and through the crossover mechanism intotheinner tubing string. Because there is more steam available than can beexhausted through the crossover mechanism into the inner conduit, a backpressure develops within the outer pumping chamber and within the casingoutwardly of the pumping mechanism. When pressure conditions across thelower check valve become substantially balanced, thelower check valvewill seat thereby entrapping the production fluid within the outerpumping chamber. Also, because of the increased pressure developed bythe back pressure condition, the steam begins to condense within theouter pumping chamber and within the casing outwardly of the pumpingmechanism. When enough of the steam has condensed and sufficientlylowered the pressure within the outer pumping chamber and the innerconduit, the condensed water will flash again to steam and force fluidagain into the inner pumping chamber, thereby initiating a subsequentpumping cycle.

The valve mechanism, including the crossover mechanism and the upper andlower check valve assemblies may be extracted from the inner conduitsimply by unlocking the landing adapter from the landing nipple andraising the inner conduit relative to the outer conduit. When thisoccurs, fluid within the inner conduit will be drained through thecrossover passages into the outer conduit and the inner conduit may beraised completely free of any hot liquid that might otherwise bedisposed above the crossover mechanism. The check valves will of courseretain a small quantity of fluid below the crossover mechanism. Theouter tubing may also be removed completely free of fluid since itslower extremity is completely open after removal of the crossovermechanism.

BRIEF DESCRIPTION OF THE DRAWINGS So that the manner in which the aboverecited fea tures, advantages and objects of the present invention, aswell as others, which will become apparent, are attained and can beunderstood in detail, more particular description of the invention,briefly summarized above,

may be had by reference to the embodiments hereof which are illustratedin the appended drawings, which drawings form a part of thisspecification.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of the invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

In the Drawings:

FIG. 1 is a sectional view of a well casing extending through a wellbore in the earths surface to an oil bearing earth formation and alsoillustrating in simple mechanical terms the provision of a pneumaticdisplacement type pump mechanism constructed in accordance with thepresent invention within the casing structure in position for pumpingproduction fluid from the well.

FIG. 2 is a fragmentary sectional view of the well and pumping mechanismof FIG. 1 illustrating the landing nipple and landing adapter structureswith the cross over passages formed therein, showing the mechanismseated at its operative position.

FIG. 3 is a fragmentary sectional view of the mechanism of FIG. 2illustrating the liquid pumping mecha- I nism of the present inventionas being unseated and moved upwardly relative to the landing nipple forex traction of the same from the well.

FIG. 4 is a schematic view of an oil production system wherein aninjection well is provided which injection well is surrounded by anumber of production wells, each of which being capable or producing oilthat migrates outwardly away from the injection well because of theformation pressure that is created at the injection well by fireflooding operations or by injection of steam into the formation. 1

FIG. 5 is a fragmentary sectional view of the upper extremity of a fluidpumping mechanism constructed in accordance with the present inventionand illustrating a modified well head structure and its valvedconnection to a flow line.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings for amore detailed understanding of the present invention and referring Ispecifically to FIG. 1, there is depicted in partial section a typicalearth formation having a well bore drilled in intersecting relation withan oil bearing stratum of the formation. As shown in FIG. 1 of thedrawings, A represents overburden of the formation while B represents aporous oil bearing portion of the formation, typically referred to asoil sand. The oil sand may be quite thin, in the order of 4 to 5 feetthick or it may well be 50 to 100 feet in thickness or greater. Inshallow oil wells the oil sand will typically be in the order of 4 tofeet in thickness. Below the oil sand B there typically exists anotherearth formation C, referred to as water sand, which contains eitherfresh or saltwater depending upon the particular environment involvedand an oil water contact level or interface 10 will typically exist.

The well bore 12 in the earth formation will typically be drilled tosufficient depth for setting of a casing 14 in the earth formation,which casing may extend slightly below the upper level of the oil sand.Ordinarily, a cement 16 is employed to firmly secure the casing 14 tothe wall structure defining the bore 12 in the earth formation. As thecasing is cemented, a plug of cement is formed at the bottom of thecasing and,

subsequent to setting of the cement, the plug will be drilled out and abore 18 will be drilled or otherwise formed through the oil sand B andslightly into the water sand C below the level of the oil/waterinterface 10. A perforated element 20, typically referred to as ascreen, may then be inserted through the casing 14 to a position withinthe bore 18 with the lower perforations of the screen substantially atthe oil/water interface. If desired, the lower portion of the casing 14may be provided with an internal landing flange 22 cooperating with anexternal flanged portion 24 formed on the screen 20 for supporting thescreen in proper position relative to the casing. A packer 26 may beinterposed between the screen and casing to retain the screen inposition relative to the casing and to establish a sealed relationshipbetween the screen and the casing.

As shown in FIG. 4, an injection well 28 and a plurality of productionwells 30 are drilled in the earth to the oil bearing formation or oilsand B and each ofthe wells may have a casing and screen structureessentially as depicted in FIG. 1. The injection well 28, however, willbe suitably connected to a generating facility 32 capable of generatingthe compressed gaseous medium that is to be employed in order to bothheat and pressurize the oil bearing earth formation and cause migrationof the oil away from the injection well 28 toward the production wells30.

At this point it should be understood that the crude oil that istypically produced in flooding operations, where such operations be fireflooding or steam flooding, is a viscous crude petroleum product which,cannot be efficiently produced from the formation by pumping because theviscous crude oil will not flow through the formation of its own accordin order that it may be pumped by mechanically driven pumps. It istypical for such oil bearing formations to be under little or noformation pressure and, therefore, the oil will not be caused to migrateby pressure toward the reduced pressure area defined by a productionwell. It is necessary, therefore, in order to produce viscous crude oilof such nature, to heat the crude oil and thereby reduce its viscosityto a readily flowable nature and to provide artificial formationpressure in order that the oil contained within the formation may becaused by such pressure to migrate toward a producton well, where it maybe produced by any number of acceptable methods. One suitable method ofdeveloping heat and pressure necessary for production of viscous crudeoil from shallow earth formations is typically referred to as fireflooding. In fire flooding operations heat in the oil bearing earthformation is created by actual burning of some of the crude oil that islocked within the formation and such burning, in addition to developinga formation pressure because of the expansion of gases during theburning operation, also produces sufficient heat to reduce the viscosityof the crude oil to a consistency where flowing will readily occur. Airor any other gasiform fluid medium containing a controlled amount ofoxygen to support combustion of the crude oil is injected into the oilbearing earth formation through an injection well. The air is injectedat sufficient pressure to cause combustion of a small amount of thecrude oil that is locked in the earth formation.

Another acceptable method of generating heat and pressure for productionof viscous crude oil is known as steam flooding where superheated steamis injected into the oil bearing earth formation through an injectionwell. The steam when generated may be in the order of 400F and may be inthe order of 250 to 350F when entering the oil bearing earth formationand the steam may be injected into the well at a pressure in the orderof 300 psi. The steam will migrate through the oil bearing earthformation and cause the oil entrapped therein to be reduced in viscositysuch that it migrates along with the steam to the production wellssurrounding the injection well. As the oil migrates outwardly away fromthe injection well due to the formation pressure that is developed bythe steam, it is simultaneously drawn toward the production wells due tothe low pressure condition that is developed as migrating oil and steamenter the production wells and is pumped to the surface.

Ordinarily, fluid displacement type pumping mechanisms that are employedto produce wells wherein heat and pressure are induced by steam or fireflooding operations employ pumping mechanisms that must be placed at aconsiderable level above the oil/water interface that is established atthe level of the screen, because vaporization or flashing of excessiveamounts of the water content of the production fluid into steam willinterfere with the pumping operation. When the water content of theproduction fluid vaporizes into steam, which vaporization is typicallyreferred to as flashing," the steam vapor may establish .a vapor lockedcondition between the check valves of the apparatus. When this occurs,pressure changes within the pumping mechanism merely achieve compressionof the vapor between the check valves but the check valves will remainclosed and prevent any fluid from passing through the pumping mechanism.It is therefore considered necessary to place the pumping mechanismsufficiently above the oil/water contact level within the well that ahydrostatic head of fluid within the well will prevent flashing of thewater content of the oil into steam.

The present invention, however, is specifically designed to utilizeflashing or vaporization of the water content of the oil into steam forthe purpose of providing a motive force that causes a flowing conditionto exist within the pumping mechanism. In accordance with the presentinvention, one suitable fluid displacement type pumping mechanism thatutilizes vaporization of the water content of the production fluid forassistance in production of fluid from the well may conveniently taketheform illustrated in FIG. 1 where a well head, illustrated generally at34, is disposed at the upper extremity of the casing 14 and provides aphysical structure for supporting a pumping mechanism within the well.An outer conduit 36 may be removably supported by the well head 34 andmay extend downwardly through the casing to a level slightly above theupper extremity of the screen 20. A landing nipple 38 having anexternally threaded portion 40 may be received by internal threads 42defined within the lower extremity of the outer conduit 36. An internallocking groove 44 may be formed in the landing nipple 38 and may receivea locking mechanism 46 of a landing adapter 48 that may be secured inany suitable manner to the lower extremity of an inner conduit 50 thatis also removably supported adjacent the upper extremity thereof by theouter conduit 36 and a sealed relationship may be established betweenthe inner and outer conduits by means of a packing device 52.

As illustrated in detail in FIGS. 2 and 3, the landing adapter 48 may beprovided with an internally threaded connector flange 54 that mayreceive the externally threaded portion 56 of the inner conduit 50,thereby causing the inner conduit to support the landing adapter and thepump mechanism carried thereby.

Again referring to FIG. 1 and also referring to FIGS. 2 and 3, an outerpump conduit 58 may be provided having an internally threaded upperextremity 60 that may be threadedly secured to the landing adapter byexternal threads 62 formed on a reduced diameter portion of the landingadapter. An internally threaded flange 64 may depend from the landingadapter and may receive the externally threaded upper extremity 66 of aninner pump conduit 68 thereby supporting the inner pump conduit from thelanding adapter.

It will be desirable to control the flow of production fluid from theformation into the casing and into the pump mechanism and to providesuch control the present invention may incorporate a valving mechanismessentially as depicted in FIG. 1 of the drawings where the outer pumpconduit 58 may be provided with a valve seat and cage structure 70 atthe lower extremity thereof. A valve ball 72 may be disposed within thevalve cage structure and may ordinarily rest in engagement with acircular valve seat 74 to provide a seal that separates an outer pumpingchamber 76 from the casing. The ball 72 serves a check valve functionand will be moved upwardly from the seat 74 by pressure differentialacross the ball 72 in order to allow production fluid to enter into thechamber 76 from the formation. A cage 78 will prevent the ball 72 frombeing completely displaced from the valve and cage assembly but willallow production fluid to flow freely past the valve ball when such flowis initiated.

A ball and cage assembly 80 is likewise disposed at the lower extremityof the inner pump conduit 68 having a ball type check valve 82 thatengages a seat 84 to restrict downward flow of production fluid and torespond to upward flow of production fluid caused by a predeterminedpressure differential to move upwardly from its seat 84 and allow theflow of production fluid into an inner pumping chamber 86. A cageelement 88 prevents the valve ball 82 from being completely displacedfrom the check valve and cage assembly 80.

The inner conduit 50 may represent an injection chamber through which apressurized medium is introduced into the well to cause controlledpumping actuation. It is desirable that communication be establishedbetween the injection chamber 90 and the outer pumping chamber 76 andsuch communication may be conveniently established by intersectingcrossover passages 92 and 94 that may be formed in the landing adapter48.

The annulus between the outer conduit 36 and the inner conduit 50 maydefine a flow passage 96 that serves to conduct produced fluid from thepumping mechanism to the well head structure where it may beconveniently carried from the well head by means of a flow conduit 98 toany suitable storage or handling facility. It is desirable that the flowpassage 96 be in fluid communication with the inner pumping chamber 86and such communication may be conveniently established by means ofintersecting crossover passages 100 and 102, also defined within thelanding adapter 48.

To provide for controlled actuation of the pumping mechanism it will bedesirable to selectively communicate the pumping mechanism with a sourceS of pressurized medium such as air and to selectively vent theinjection chamber 90. Accordingly, the inner conduit 50 may be providedwith a T-connection 104 at the upper extremity thereof, whichT-connection may be connected to an actuating fluid supply conduit 106and a vent conduit 108. Pressurized fluid such as air may be injectedfrom the source S into the injection chamber 90 defined by the innerconduit 50 under control of an automatic valve 110 that is selectivelyenergized by a controller mechanism 112. The controller mechanism alsoactuates an automatic vent valve 114 that serves to vent the injectionchamber 90 to the atmosphere or to any other suitable receiver for thevented fluid from the injection chamber.

OPERATION Steam assisted operation of the pumping mechanism may becharacterized by venting of the injection cham ber 90 through the ventconduit 108 with the valve 114 in its open condition at the end of anoperative cycle of the pumping mechanism. After the inner and outerpumping chambers and the flow chamber have become filled to a suitablelevel with production fluid entering from the formation, which formationflow of production fluid will be discussed hereinbelow a pumping cyclewill be initiated by the controller 112 which causes closure of the ventvalve 114 and simultaneously opens the injection valve 110 therebycausing pressurized medium to flow from the source S to the conduit 106and into the injection chamber 90 defined by the inner conduit 50. Whensteam assisted pumping opera tion is employed, the injected fluid willbe air or any other suitable gas which will be at a much lowertemperature than the temperature of .the superheated steam present inthe pumping mechanism and within the chamber 90.

As the low temperature medium is injected into the chamber 90 itcondenses the steam vapors that are present in the injection chamber andthe water, so condensed, descends to the level of the crossover passages92 and 94 in the landing adapter 48, whereupon the water will flowthrough the crossover passages into the outer pumping chamber 76. Whenthe water that has resulted from the condensation within the chamber 90passes through the crossover passages into the chamber 76, an immediatepressure change occurs due to forcing of the water through therestricted passages 92 and 94 and due to the much larger dimension ofthechamber 76. The pressure drop occurring as the superheated water entersthe outer pump chamber causes at least a portion of the water content ofthe fluid to flash into steam, creating enough of an explosive effectthat causes the liquid within the outer pumping chamber to be forcedthrough the check valve mechanism 80 into the inner pumping chamber 86and simultaneously causes liquid in the inner pumping chamber to beforced through the crossover passages 100 and 102 into the flow chamber96.

Because the flow chamber 96 is of much larger dimension than thedimension of the inner pumping chamber 86 and because the liquid isforced through the restricted crossover passages 100 and 102 a pressuredrop will be developed within the chamber 96 causing a portion of thewater content of the production fluid flowing into the chamber 96 toimmediately flash into steam. The steam serves to lighten the liquidcolumn within the chamber 96 and cause an upward flowing effect therebycarrying the liquid upwardly within the flow chamber to the well headstructure where it exits through the flow conduit 98. With less than 50pounds offlow line pressure the fluid moves to a storage facility suchas a tank battery, where it is stored under atmospheric conditions untilit is transported away for further handling.

At this time the injection valve 110 will be closed and the vent valve114 will be opened thereby venting the injection chamber through theconduit 108 to the atmosphere or to any other suitable receiver for thevented gaseous medium. When this occurs the outer pumping chamber 76will also be communicated to the atmosphere through the crossoverpassages 92 and 94 and the inner conduit 50. As such venting decreasesthe pressure condition within the outer pumping chamber below thepressure of the liquid disposed in the annulus between the screen andthe outer pump conduit 58. When this occurs the pressure differentialacross the contact area between the valveball 72 and the valve seat 74will cause the ball to move upwardly thereby communicating the screenchamber with the outer pumping chamber 76 thereby venting the screenannulus through the outer pumping chamber, the restricted crossoverpassages and 102 and the injection chamber 90 to the vent conduit 108.As the pressure decreases in the screen annulus, the water content ofthe fluid within the screen annulus, because of its high temperature, inthe order of 250 to 350F will immediately flash to steam, therebycreating-steam pressure within the screen annulus that forces liquidcontained therein through the check valve assembly and into the outerpumping chamber 76. In view of the fact that steam is continuouslygenerated while the vent valve 114 is open, the steam in traversing therestricted crossover passages 100 and 102 will develop a back pressurewithin the outer pumping chamber 76 and within the annulus between thescreen and the outer pump conduit 58. After the pressure induced by thesteam has increased to a predetermined level, the steam will begin tocondense within the screen annulus and liquid will be forced through thecheck valve mechanism 70 into the outer pumping chamber 76 completingthe pumping cycle. The next pumping cycle will be initiated simply bythe controller 112 which reverses the surface valves opening the valveand closing the vent valve 114 in the manner discussed above.

Although the controller may be utilized for cyclically introducing apressurized cool gas into the injection chamber 90 and venting theinjection chamber to cause displacement type pumping actuation in themanner described above, it has been determined that displacement pumpingof production fluid will occur automatically without cyclic operation ofthe valves after the pumping operation has been initiated. As long assteam is continuously introduced into the formation through an injectionwell and enters the well bore through the oil sand along with migratedcrude oil, the pump mechanism will automatically pump production fluidfrom the oil bearing formation and conduct it to the flow conduit 98 aslong as a back pressure of less than b 50 psi is maintained on the flowconduit. It has been determined that a back pressure less than 50 psi inthe flow conduit will allow the pumping operation to be automaticallyaccomplished without cyclic operation of the valves 110 and 114 as longas the pump mechanism within the well is disposed at a sufficient levelrelative to the screen to prevent a hydrostatic head from developingabove the screen to the point that flashing of steam is prevented in theannulus between the screen and the outer pump conduit 58. With thecontrol valves closed condensation will occur naturally within theinjection passage 90 and the condensed fluid in the injec tion passagewill flow through the restricted crossover passages into the outer pumpchamber where flashing of the steam content of the liquid will occurbecause of the pressure differential caused by flow across therestricted passages and the flashing will force liquid within the outerpumping chamber into the inner pumping chamber and through therestricted crossover passages 100 and 102 into the flow chamber 96.Flashing of steam will occur in the flow chamber because of the pressuredifferential existing across the restricted passages 100 and 102 therebycausing the liquid column within the flow passage to be lightened andforced upwardly where it is produced through the flow conduit.

In order for the pumping actuation to occur automatically withoutcycling of the valves, it is necessary that the water content of theproduction fluid be quite high. It is therefore desirable to place thelower extremity of the pump mechanism as close as conveniently possibleto the oil water contact level within the well and such can beaccomplished in accordance with the present invention by placing thelower extremity of the pumping mechanism within the screen as shown inFIG. 1. It is also necessary in order for pumping actuation to beconducted automatically that back pressure on the flow conduit and flowchamber be as low as conveniently possible. It has been determined thatback pressure should be below 50 psi in order to achieve automaticoperation of the pumping mechanism without cycling of the valves.

It has also been determined that displacement pumping will occur whenthe valves are cycled and yet when no pressurized gaseous medium isintroduced into the injection chamber 96 but only after injectioninduced cycling has occurred for a particular period of time. Flashingof the steam as it is forced in the form of high temperature waterthrough the restricted crossover passages in the landing adapter willoccur automatically and will induce pressurized fluid movement withinthe pumping mechanism to produce an oil water mixture in the flowconduit even though cycling of the valves by the controller does notinduce injection of a pressurized gaseous medium into the injectionchamber 90.

Referring now to FIG. there is disclosed a modified embodiment of thewell head structure wherein a well head illustrated generally at 116includes conduits 118 and 120 that extend from the casing and arecontrolled respectively by valves 122 and 124. An outer conduit 126 maybe supported by the well head and may extend into the well casing insimilar manner as illustrated in FIG. 1. An inner conduit 128 may besupported by the outer conduit 126 and may extend downwardly into theouter conduit in the same manner as shown in FIG. 1 with a sealedrelationship between the inner and outer conduits being established bymeans of a stuffing box 130. An injection conduit 132 controlled by aninjection valve 134 may control introduction of pressurized gaseousmedium from a source S similar to the source S illustrated in FIG. 1. Anexhaust conduit 136 controlled by an exhaust valve 138 may also bedisposed in communication with the conduit 128 in order to exhaust aninjection chamber in similar manner as discussed above in connectionwith FIG. 1.

A flow conduit 140 may extend from the outer conduit I26 and may becontrolled by means of a flow valve 142 to conduit produced fluid to asuitable storage facility. The flow conduit 140 may communicate with theconduit and may further be provided with a pressure gauge 146 inorder-to monitor the pressure of the flow conduit.

A controller 148 may be provided for control of the automatic valves 134and 138 in the manner discussed above in connection with FIG. 1 in orderto cause pressure induced cycling of the pumping mechanism or to causecycling of the valves as appropriate in order to achieve automaticactuation of the pumping mechanism. The pumping mechanism of the wellstructure set forth in FIG. 5 will function in identical manner to thatillustrated in FIG. 1.

In view of the foregoing it is clearly apparent that I have provided anovel displacement type pumping mechanism that provides the capabilityof fluid pressure induced or automatic fluid displacement pumping of aproduction fluid from an oil bearing earth formation. It is apparentthat the present invention is one well adapted to attain all of theobjects hereinabove set forth together with other advantages which willbecome obvious and inherent from a description of the apparatus itself.It will be understood that certain combinations and subcombinations areof utility and may be employed without reference to other features andsubcombinations. As many possible embodiments may be made of theinvention without departing from the spirit or scope thereof, it is tobe understood that all matters herein set forth or shown in theaccompanying drawings are to be interpreted as illustrative and not in alimiting sense.

What is claimed is:

1. Apparatus for flowing liquid from a well bore extending from thesurface of the earth to a liquid bearing earth formation, said apparatuscomprising:

casing means extending into said well bore and defining a well head atthe upper extremity thereof, said casing being in fluid communicationwith said liquid bearing earth formation;

outer conduit means being supported by said well head and extending intosaid casing;

a landing nipple being coupled to the lower extremity of said outerconduit means and defining support means;

inner conduit means being removably supported by said well head andextending into said outer conduit means, said inner conduit meanscooperating with said outer conduit means to define flow chamber means;

landing adapter means being coupled to said inner conduit means andbeing releasably and sealingly engaged with said landing nipple;

outer pump conduit means being supported in sealed relation by saidlanding adapter means and depending therefrom, said outer pump conduitdefining a pressure imposing chamber;

first valve means being carried by said outer pump conduit means andallowing unidirectional flow of said production liquid from said casingmeans into said pressure imposing chamber;

inner pump conduit means being supported by said landing adapter means,said inner pump conduit means extending into said pressure imposingchamber and being in fluid communication with said outer conduit means;second valve means being carried by said inner pump conduit means andallowing unidirectional flow of said production liquid from saidpressure imposing chamber to said flow chamber means; means forselectively introducing pressurized fluid into said pressure imposingchamber; and means for conducting produced liquid from said flow chambermeans. 2. Apparatus as recited in claim 1, wherein: said pressureimposing chamber is in fluid communication with said inner conduitmeans; and said flow chamber means is in fluid communication with saidouter conduit means, outwardly of said inner conduit means. 3.Apparatusas recited in claim 1, wherein: said landing adapter means hasfirst crossover passage means formed therein communicating said innerconduit means with the annulus between said inner and outer pump conduitmeans and second crossover passage means communicating said inner pumpconduit means with the annulus between said inner and outer conduitmeans. 4. Apparatus as recited in claim 1, wherein: said landing nippleis connected to the lower extremity of said outer conduit means; saidlanding'adapter is connected to the lower extremity of said innerconduit means; and said inner and outer pump conduit means are connectedto the lower extremity of said landing adapter. 5. Apparatus as recitedin claim 1, including: perforated means secured to the lower extremityof said casing means and having perforations formed thereincommunicating said liquid bearing earth formation with said casingmeans. 6. Apparatus as recited in claim 5, wherein: at least a portionof said inner and outer pump conduit means extend into said casing to alevel disposing said first valve means below the level of productionliquid within said casing and perforated means. 7. A method ofdisplacement pumping of a production fluid including crude oil and waterfrom an oil bearing earth formation wherein production and injectionwells are formed in the earth and are in communication with saidformation and at least one injection well continuously injects steaminto said oil bearing earth formation and wherein said production wellseach have apparatus defining an injection chamber, a production fluidsupply chamber being open to said formation and receiving productionfluid from said formation, a first pumping chamber having valvedcommunication with said production fluid supply chamber, a secondpumping chamber having valved communication with said first pumpingchamber and a flow chamber being disposed in communication with saidsecond pumping chamber, said method comprising the steps of:

causing production fluid including steam, water and crude oil to entersaid first pumping chamber from said production fluid supply chamber;condensing at least a portion of said steam in said first pumpingchamber into water;

causing flashing of a portion of the water content of said productionfluid into steam in said first pumping chamber and causing steampressure forcing of liquid and steam from said first pumping chamber 5to said second pumping chamber;

condensing at least a portion of the steam content of said productionfluid in said second pumping chamber into water; causing flashing of aportion of the condensed water of said liquid in said second pumpingchamber to steam and causing steam pressure forcing of said liquid andsteam from said second pumping chamber to said flow chamber; condensingat least a portion of the steam content of said production fluid in saidflow chamber into water; and causing flashing of a portion of thecondensed water of said production fluid in said flow chamber to lightenthe column of the liquid in said flow chamber and to cause steam forcingof liquid from said flow chamber for production. 8. The method of claim7, wherein: said condensing of said steam in said first pumping chamberis accomplished by injecting a fluid under pressure into said injectionchamber at a lower temperature than the temperature of the steam withinsaid injection chamber. 9. The method of claim 7, wherein: said injectedfluid is air.

10. The method of claim 7, wherein: steam entering said production fluidsupply chamber from said formation is caused to condense in saidproduction fluid supply chamber by controlled modification of the steamgenerated pressure condition within said production fluid supplychamber. 11. The method of claim 8, wherein the steps of claim 7 occurrepetitively to' induce cyclic displacement pumping actuation andincluding the steps of:

discontinuing injection of fluid into said injection chamber aftercyclic displacement pumping actuation of said pumping has been conductedin accordance with the steps of claim 7 for a predetermined period oftime; continuing with cyclic displacement pumping actuation inaccordance with the steps of claim 7 in absence of injection of saidfluid medium; and maintaining a predetermined back pressure on said flowchamber after discontinuing injection of fluid into said injectionchamber to allow controlled and substantially continuous flashing of atleast a portion of the water content of said production fluid into steamwithin said flowchamber. 12. Apparatus for flowing production fluidincluding a mixture of oil and water from an oil bearing earth formationwherein the earth formation is heated and pressurized by injection of afluid into the formation and at least one production well bore extendsto the formation, said apparatus comprising:

casing means extending into said well bore and defining a well head atthe upper extremity thereof, said casing means being in fluidcommunication with said oil bearing earth formation; means communicatingsaid casing means with said formation; pump means being disposed withinsaid casing and defining an injection chamber, a flow chamber and firstand second pumping chambers, said pump means defining first restrictedpassage means communicating said injection chamber and said firstpumping chamber and defining second restricted passage meanscommunicating said second pumping chamber and said flow chamber;

first valve means controlling the flow of production fluid from saidcasing into said first pumping chamber, said inlet of said valve meansbeing disposed sufficiently near the oil/water contact within saidcasing to prevent the hydrostatic head of the column of fluid withinsaid well from interfering with flashing of the water content of saidproduction fluid into steam;

second valve means controlling the flow of production fluid from saidfirst pumping chamber to said second pumping chamber; and

means for selectively controlling injection of a pressurized medium intosaid injection chamber and venting of said injectionchamber.

13. Apparatus as recited in claim 12, wherein:

said means for defining said flow chamber comprises outer conduit meanssuspended within said casing by said well head; and

said means defining said injection chamber comprises an inner conduitmeans suspended by said well head within said outer conduit means.

14. Apparatus as recited in claim 12, wherein:

said means communicating said casing means with said formation isperforated means disposed at the lower extremity of said casing means,said perforated means having been perforated along the length thereof toallow production fluid to enter said casing means from said formation,the lower extremity of said perforated means extending below theoil/water level within said formation. 15. Apparatus as recited in claim13, wherein: said first valve means is disposed in juxtaposed relationwith said oil/water level. 16. Apparatus as recited in claim 14,wherein: said pump means extends at least partially within saidperforated means. 17. Apparatus as recited in claim 12, including: meansfor maintaining a minimum of back pressure on the production fluidflowing through said flow chamber to allow continuous flashing of thewater content of said production fluid into steam. 18. Apparatus forflowing production fluid including a mixture of oil and water from anoil bearing earth formation wherein the earth formation is heated andpressurized by injection of a fluid into the formation and at least oneproduction well bore extends to the formation, said apparatuscomprising:

casing means extending into said well bore and defining a well head atthe upper extremity thereof, said casing means being in fluidcommunication with said oil bearing earth formation; first and secondcasing valves communicating said casing with a flow line and with a ventconduit, respectively, said casing valves being closed during operationof said apparatus and being opened to balance the pressure conditions insaid flow chamber and said casing; pump means being disposed within saidcasing and defining an injection chamber, a flow chamber and first andsecond pumping chambers, said pump means defining first restrictedpassage means communicating said injection chamber and said firstpumping chamber and defining second restricted passage meanscommunicating said second pumping chamber and said flow chamber, saidflow chamber being in communication with said flow line; flow valvemeans connected in said flow line and controlling flow of productionfluid from said flow chamber; first check valve means controlling theflow of production fluid from said casing into said first pumpingchamber, said inlet of said first check valve means being disposedsufficiently near the oil/water contact within said casing to preventthe hydrostatic head of the column of fluid within said well frominterfering with flashing of the water content of said production fluidinto steam; second check valve means interposed between said first andsecond pumping chambers and controlling the flow of production fluidfrom said first pumping chamber to said second pumping chamber; a sourceof pressurized medium; injection conduit means interconnecting saidsource and said injection chamber; valve means in said injection conduitfor selectively controlling injection of pressurized medium from saidsource into said injection chamber; an exhaust conduit beingcommunicated with said injection chamber; and valve means in saidexhaust conduit being controllable for venting of said injectionchamber.

l l l= =l l

1. Apparatus for flowing liquid from a well bore extending from thesurface of the earth to a liquid bearing earth formation, said apparatuscomprising: casing means extending into said well bore and defining awell head at the upper extremity thereof, said casing being in fluidcommunication with said liquid bearing earth formation; outer conduitmeans being supported by said well head and extending into said casing;a landing nipple being coupled to the lower extremity of said outerconduit means and defining support means; inner conduit means beingremovably supported by said well head and extending into said outerconduit means, said inner conduit means cooperating with said outerconduit means to define flow chamber means; landing adapter means beingcoupled to said inner conduit means and being releasably and sealinglyengaged with said landing nipple; outer pump conduit means beingsupported in sealed relation by said landing adapter means and dependingtherefrom, said outer pump conduit defining a pressure imposing chamber;first valve means being carried by said outer pump conduit means andallowing unidirectional flow of said production liquid from said casingmeans into said pressure imposing chamber; inner pump conduit meansbeing supported by said landing adapter means, said inner pump conduitmeans extending into said pressure imposing chamber and being in fluidcommunication with said outer conduit means; second valve means beingcarried by said inner pump conduit means and allowing unidirectionalflow of said production liquid from said pressure imposing chamber tosaid flow chamber means; means for selectively introducing pressurizedfluid into said pressure imposing chamber; and means for conductingproduced liquid from said flow chamber means.
 2. Apparatus as recited inclaim 1, wherein: said pressure imposing chamber is in fluidcommunication with said inner conduit means; and said flow chamber meansis in fluid communication with said outer conduit means, outwardly ofsaid inner conduit means.
 3. Apparatus as recited in claim 1, wherein:said landing adapter means has first crossover passage means formedtherein communicating said inner conduit means with the annulus betweensaid inner and outer pump conduit means and second crossover passagemeans communicating said inner pump conduit means with the annulusbetween said inner and outer conduit means.
 4. Apparatus as recited inclaim 1, wherein: said landing nipple is connected to the lowerextremity of said outer conduit means; said landing adapter is connectedto the lower extremity of said inner conduit means; and said inner andouter pump conduit means are connected to the lower extremity of saidlanding adapter.
 5. Apparatus as recited in claim 1, including:perforated means secured to the lower extremity of said casing means andhaving perforations formed therein communicating said liquid bearingearth formation with said casing means.
 6. Apparatus as recited in claim5, wherein: at least a portion of said inner and outer pump conduitmeans extend into said casing to a level disposing said first valvemeans below the level of production liquid within said casing andperforated means.
 7. A method of displacement pumping of a productionfluid including crude oil and water from an oil bearing earth formationwherein production and injection wells are formed in the earth and arein communication with said formation and at least one injection wellcontinuously injects steam into said oil bearing earth formation andwherein said production wells each have apparatus defining an injectionchamber, a production fluid supply chamber being open to said formationand receiVing production fluid from said formation, a first pumpingchamber having valved communication with said production fluid supplychamber, a second pumping chamber having valved communication with saidfirst pumping chamber and a flow chamber being disposed in communicationwith said second pumping chamber, said method comprising the steps of:causing production fluid including steam, water and crude oil to entersaid first pumping chamber from said production fluid supply chamber;condensing at least a portion of said steam in said first pumpingchamber into water; causing flashing of a portion of the water contentof said production fluid into steam in said first pumping chamber andcausing steam pressure forcing of liquid and steam from said firstpumping chamber to said second pumping chamber; condensing at least aportion of the steam content of said production fluid in said secondpumping chamber into water; causing flashing of a portion of thecondensed water of said liquid in said second pumping chamber to steamand causing steam pressure forcing of said liquid and steam from saidsecond pumping chamber to said flow chamber; condensing at least aportion of the steam content of said production fluid in said flowchamber into water; and causing flashing of a portion of the condensedwater of said production fluid in said flow chamber to lighten thecolumn of the liquid in said flow chamber and to cause steam forcing ofliquid from said flow chamber for production.
 8. The method of claim 7,wherein: said condensing of said steam in said first pumping chamber isaccomplished by injecting a fluid under pressure into said injectionchamber at a lower temperature than the temperature of the steam withinsaid injection chamber.
 9. The method of claim 7, wherein: said injectedfluid is air.
 10. The method of claim 7, wherein: steam entering saidproduction fluid supply chamber from said formation is caused tocondense in said production fluid supply chamber by controlledmodification of the steam generated pressure condition within saidproduction fluid supply chamber.
 11. The method of claim 8, wherein thesteps of claim 7 occur repetitively to induce cyclic displacementpumping actuation and including the steps of: discontinuing injection offluid into said injection chamber after cyclic displacement pumpingactuation of said pumping has been conducted in accordance with thesteps of claim 7 for a predetermined period of time; continuing withcyclic displacement pumping actuation in accordance with the steps ofclaim 7 in absence of injection of said fluid medium; and maintaining apredetermined back pressure on said flow chamber after discontinuinginjection of fluid into said injection chamber to allow controlled andsubstantially continuous flashing of at least a portion of the watercontent of said production fluid into steam within said flow chamber.12. Apparatus for flowing production fluid including a mixture of oiland water from an oil bearing earth formation wherein the earthformation is heated and pressurized by injection of a fluid into theformation and at least one production well bore extends to theformation, said apparatus comprising: casing means extending into saidwell bore and defining a well head at the upper extremity thereof, saidcasing means being in fluid communication with said oil bearing earthformation; means communicating said casing means with said formation;pump means being disposed within said casing and defining an injectionchamber, a flow chamber and first and second pumping chambers, said pumpmeans defining first restricted passage means communicating saidinjection chamber and said first pumping chamber and defining secondrestricted passage means communicating said second pumping chamber andsaid flow chamber; first valve means controlling the flow of productionfluid from said casing into said first pumping chamber, said inlet ofsaid Valve means being disposed sufficiently near the oil/water contactwithin said casing to prevent the hydrostatic head of the column offluid within said well from interfering with flashing of the watercontent of said production fluid into steam; second valve meanscontrolling the flow of production fluid from said first pumping chamberto said second pumping chamber; and means for selectively controllinginjection of a pressurized medium into said injection chamber andventing of said injection chamber.
 13. Apparatus as recited in claim 12,wherein: said means for defining said flow chamber comprises outerconduit means suspended within said casing by said well head; and saidmeans defining said injection chamber comprises an inner conduit meanssuspended by said well head within said outer conduit means. 14.Apparatus as recited in claim 12, wherein: said means communicating saidcasing means with said formation is perforated means disposed at thelower extremity of said casing means, said perforated means having beenperforated along the length thereof to allow production fluid to entersaid casing means from said formation, the lower extremity of saidperforated means extending below the oil/water level within saidformation.
 15. Apparatus as recited in claim 13, wherein: said firstvalve means is disposed in juxtaposed relation with said oil/waterlevel.
 16. Apparatus as recited in claim 14, wherein: said pump meansextends at least partially within said perforated means.
 17. Apparatusas recited in claim 12, including: means for maintaining a minimum ofback pressure on the production fluid flowing through said flow chamberto allow continuous flashing of the water content of said productionfluid into steam.
 18. Apparatus for flowing production fluid including amixture of oil and water from an oil bearing earth formation wherein theearth formation is heated and pressurized by injection of a fluid intothe formation and at least one production well bore extends to theformation, said apparatus comprising: casing means extending into saidwell bore and defining a well head at the upper extremity thereof, saidcasing means being in fluid communication with said oil bearing earthformation; first and second casing valves communicating said casing witha flow line and with a vent conduit, respectively, said casing valvesbeing closed during operation of said apparatus and being opened tobalance the pressure conditions in said flow chamber and said casing;pump means being disposed within said casing and defining an injectionchamber, a flow chamber and first and second pumping chambers, said pumpmeans defining first restricted passage means communicating saidinjection chamber and said first pumping chamber and defining secondrestricted passage means communicating said second pumping chamber andsaid flow chamber, said flow chamber being in communication with saidflow line; flow valve means connected in said flow line and controllingflow of production fluid from said flow chamber; first check valve meanscontrolling the flow of production fluid from said casing into saidfirst pumping chamber, said inlet of said first check valve means beingdisposed sufficiently near the oil/water contact within said casing toprevent the hydrostatic head of the column of fluid within said wellfrom interfering with flashing of the water content of said productionfluid into steam; second check valve means interposed between said firstand second pumping chambers and controlling the flow of production fluidfrom said first pumping chamber to said second pumping chamber; a sourceof pressurized medium; injection conduit means interconnecting saidsource and said injection chamber; valve means in said injection conduitfor selectively controlling injection of pressurized medium from saidsource into said injection chamber; an exhaust conduit beingcommunicaTed with said injection chamber; and valve means in saidexhaust conduit being controllable for venting of said injectionchamber.